Electric switch



Nov. 6, 1951 W. C, LESHER 2,574,400

ELECTRIC SWITCH Filed Aug. l, 1947 2 SHEETS--SHEET l 0' l gx, Immllll' I fillwifjilll'" Il Ilm/enrol William C. Lesher' b5 His Aforn'g Nov. 6, 1951 w. c. LESHER 2,574,400

ELECTRIC SWITCH Filed Aug. l, 1947 2 SHEETS--SHEET 2 Im/enor' William C. Leshev bi1 'Ii ATToPnenq Patented Nov. 6, 1.951

UNITED STATES PATENT OFFICE 2,574,400 n ELEorR'Ic SWITCH WilliamV C. Lesher, Pittsfield, Mass., assignor to General Electric' Company, ya corporation of New York 14 Claims.

My invention relates to improvements in electric switches intended primarily for outdoor installation on distribution systems and more particularly to improvements in disconnectingY switches and especially fuse disconnecting switches of the opendropout type.`

Fuse disconnecting switches of the open dropout type, with which IV am familiar, have been been` mounted outwardly vfrom the insulator at' distances from each other and'from the possibly grounded metallic band support which are sufcient to `provide the dielectric strike and creepagevaluesrequired'to meet the basic insulation level of the voltage classification for which the switches are designed. However, the voltage classifications of distribution apparatus do not require and it has not been economically practical to provide, distances between the terminals and the metallic band support which are sufficient to eliminate kthe possibilities of animals producing short circuits between the terminals and'between the intervening metallic band support of' the insulator` and either terminal.' In addition to beingA economically impractical, the result oiany such expedient to obtain bird-proof distances is a" switch of extended structure and ungainly appearance.

In fuse disconnecting'swtches of thetype hav` ingan expulsion tube sealed at one end and open at the other end, the expulsion effect"V o'f the blowout action tends to move the fuse tube and theparts connected thereto in a direction away from the'open end so forcibly as to produce ma# terial shock which has to be absorbed and transmitted through the attachment of the parts to the insulator and thence to the insulator mountf ing.. In prior art fuse disconnecting switches of the open typeA embodying the metallic band support; the eect'of ythis Vexpulsion `force has been magnified many times by leverage, since the expulsion tube is mounted at considerable Adistance fromthe insulatorvin order to provide sufiicient dielectric-strike distance from the metallic band support to the fuse in the the-uninsulated solid disconnecting bladey it is customary to 'furnish Aas an alternative to the fused expulsion tube.'Y These magnified forcesref' sultin-` application? to the*y insulator of stresses expulsion tube or to such as bending for which the usually employed ceramic structure is ill adapted. In order to meet even current interrupting abilities required on normal distribution circuits'without breaking the porcelain insulator or bending the terminals 0r supporting members so they are no longer usable, it' has been proposed to have both ends of the expulsion tube open; However, the expulsion of hotionize'd conducting arc gases from' the energized4 end of the tube creates a hazardv fromV arcover to nearby grounded parts or even be tween" associated, electrically energized overhead lines or apparatus terminals. In view of this hazard', variousmethods have been proposed to limitl the range of currents at 'which expulsion action'occurs at both ends or to direct the expel'- ling ojthe gasv away from associatedV lines or apparatus. Each of `these expedients only slightly., lessens the hazard. The only positive corrective measure Vis to seal the endof the expulsiontube which remains energized after the arc is extinguished in the tube since tests'have shown that the hot conducting'arc gases expelled from the' tube'can cause ashover to ground members, or those excited at a diiierent potential, even when located from five to six feet from the terminal on the energizedend of the expulsion tube whereas no iiashoverwill occur to such grounded or ener-1 gized members even when located only six inches fromthe end of the tube which is deenergiz'ed by the' arc extinguishing action of the tube. y

While open type fuse disconnecting switches ave been provided with metallic hoods for preventingv ice and like formations and ykeeping rain from the upper contact structure, such hoods have' been an integral part of the structure and, in some cases, constitute a part of the latching, arrangement. Such' hoods not only add mate-f rially tothe weight and costof theswitch,l but inasmuch as they cannot beelimi'natedwithout change vin structure, they necessitate they manufacture of two lines of switches'onewith hoods andthe other without, in orderto satisfytrade demands; This, of course, adds'mate'rially'to the cost of the switches. y

VVlcfuse disconnecting switches' normally are mounted', oncrcssarms at the'to'p of the' poles supportingthe' electric distribution llines. Many times the switch is located out on the end of a,v crossarmV as much as four to five feet from the operator on the pole. It mustbfecperated 'with' a long'switch pole in orderl to reach it and also to'prevent4 the operator from coming in contactz with the electrically energized portions of the,u device; Vespecially of the openA type construction.

"vision of a hood to cover and protect the upper terminal.

It has been proposed to have disk-like bearing l or guiding surfaces on the hook and trunnions of the hinge for the expulsion tube so as to guide the free end into a hooded upper latch and terminal. However, the necessary very close machining limits on the guiding surfaces proved too costly for a class of apparatus of which so many units are required in order adequately to protect an electric distribution circuit.

An object of my invention is to provide an improved electric switch structure, particularly of y the open fuse type, such that the possibility of short circuits and false operations in consequence of birds and other wild life getting across the exposed energized metal parts of the switch is so materially reduced as to be practically eliminated. Another object of my invention is rto provide an improved electric switch structure, especially of the open fuse type, with the insulator supporting member so secured to the insulator as to permit positioning the expulsion tube in such a way that the stresses on the support caused by the expulsion or blowout effect are not magnified by extended supporting arms or terminals. Also an object of my invention is to provide an improved electric switch structure, particularly of the open type, which is compact, sturdy,V and of pleasing appearance. Still another object of my invention is to provide an improved expulsion fuse disconnecting switch of the open type wherein the expulsion force accompanying the ruptures of the fuse is absorbed and transmitted to the supporting insulator in such a manner as to minimize the effect of the shock. A further object of my invention is to provide for the contact structure of a disconnecting switch a readily and simply attachable and detachable hood of insulation which is light and economical. A still further object of my invention is to provide an improved disconnecting switch of the hook bearing type such that lateral deviation, particularly during a closing movement of the movable conducting member, is practically eliminated. These and other objects of my invention will appear in more detail hereinafter.

My invention will be better understood from the following description when considered in connection with the accompanying two sheets of drawings, and its scope will be pointed out in the appended claims.

In the accompanying drawing, Fig. 1 is a side elevation of a fused disconnecting switch of the open dropout type embodying my invention and shown in the circuit closed position; Fig. 2 is an enlarged view similar to Fig. 1 with some parts broken away for clearness of illustration and in addition showing in broken lines some intermediate positions of the movable parts; Fig. 3 is a front elevation of the switch shown in Fig. 2 with the switch shown in the full open position; Fig. 4 is a view similar to Fig. 1 illustrating the switch with the parts in position just prior to dropout and also showing in broken lines the fuse tube in an intermediate position following the blowout of the fuse and in its extreme open position; Fig. 5 is an enlarged sectional View taken on the line 5 5 of Fig. 2 illustrating the upper switch terminal structure and its mounting; and Fig. 6 illustrates a modification of my invention wherein the switch is purely a disconnecting switch without a fuse and without dropout action.

For the purpose of illustrating my invention, I have shown in Figs. 1 to 4, inclusive, a fuse disconnecting switch of the open dropout type wherein the line terminals l and 2 and associated contact structures are mounted adjacent the ends of a suitable substantially cylindrical insulator 3. In order to have a compact structural arrangement whereby to avoid multiplying the expulsion recoil forces as they stress the porcelain and supporting member and also to avoid false operations in consequence of short circuits produced when birds and other wild life Contact conducting parts of a switch, such as the terminals, for example, the insulator supporting arm 4 is mounted so a portion near one end thereof is within the cylindrical surface of the insulator 3 at the rear thereof and approximately midway of the ends of the insulator. With the supporting arm d thus extending directly from the insulator in a direction opposite to the contact structure hereinafter described, a more effective strike-over distance to the fuse I9 in tube 2l or to the metallic tube 62 shown in Fig. 6, when substituted for the tube 2l, is insured even with the tubes 2l or 62 located closer to the insulator 3 than has been possible with the heretofore used metallic band support around the outside of the middle portion of the insulator. Thus, in my construction, combine mounting of the support l in the insulator 3 at the rear 'thereof and the iocation of the tube `2l or t2 closer to the insulator 3. This provides a more economical construction for open type switches and insures not only an interrupting ability comparable with that of switches of the enclosed type but also, with minor modifications of the expulsion tube 2l and associated parts comprising current conducting means IS, a device with an interrupting ability nearly double that of the normal interrupting ability and with the end of the tube 2|. which is normally energized after arc extinguishing, sealed by the cap 22 so as to prevent strikeover to associated lines of apparatus. As illustrated in Figs. 1 and 2, arm Il is secured to a support such as a pole-mounted bracket 5 by suitable fastening means shown as a bolt 6 provided with a nut a bearing washer 3 and a lockwasher 9.

Adjacent one end of the insulator 3 and supported therefrom in conductive relation with the terminal l and so as to extend transversely of the insulator in a direction oppositely to that of the support d is a first relatively stationary contact means iii. inasmuch as the tube 2| can be located closer to insulator 3, as hereinbefore described, the stationary contact means l0 is relatively shorter than heretofore possible in devices of the prior art thus decreasing the leverage which multiplies the recoil forces from expulsion action. Supported from the other or lower end of the insulator 3, in line with the longitudinal axis thereof is a hinge means comprising a hook type bearing member l, the bearing axis I2 of which is substantially perpendicular to the longitudinal axis of the insulator and displaced from the insulator axis oppositely to the displacement Vof` thecontact means I0. At the other or lower end of the insulator 3, there is mounted on the bearing member II a second relatively stationary contact means I3 in current conducting relationship with the terminal 2. For completirlg a conducting path between the stationary contact means lil and I3 and consequently the terminals I and 2, I provide a hinge element I4 having trunnions I5 adapted to be inserted in the hooks It of the bearing element II and carrying a contact I'I movable into and out of engagement with the lower contact means I3 upon rotation of the hinge element. Also. I provide current conducting means indicated generally by I B and carried by the hinge element I 4 and rotatable therewith counterclockwise, as Viewed in the drawings, about its bearing axis I2 to the circuit closed position to establish theconducting path between the lower and upper contact means I0 and I3.

As shown in Figs. l to Li, in clusive, the current conducting means is or" the expulsion fuse type comprising a conductor I9 having a portion 2D fusible at a predetermined value of current and an expulsion tube 2 I having a conducting cap 22 connected to one end of the conductor and engageable with the upper stationary contact means I0. The fusible portion 23 of the conductor i9 is mounted within a cylindrical casing v of insulating material and is connected to the cap 22 through a stud 24 which carries the casing 23 and a button head. not shown, engageable by the cap 22 as is well known to the art, when sealing the fuse tube 2I is practical in the light of the required interrupting duty. As shown, the tube 2l is pivotally mounted at 26 on the hinge element iii constituting therewith a toggle which is held in the rigid condition shown in Figs. 1 and 2 by tightening the conductor I 9 around a thumb screw 2? in the hinge element I4 and then clamping the conductor between the element and a locked-against-turning nut 28. When the toggle is thus held rigid, the switch can be closed by inserting a switch hook in an operating eye member 29 mounted on the fuse tube 2 I.

'For maintaining the switch in the closed circuit position after turning the rigid toggle counterclockwise, as viewed in the drawings, to the closed circuit position shown in Figs. l and 2. there is provided a holding means which, as i1- lustrated, comprises a U-shaped resilient member 35, the outer ends of the legs of which are bent inwardly and then outwardly to provide, in V -shaped formation, flared ends which yield sufiiciently to permit entrance of the cap 22 and thereupon close over the cap to prevent reverse movement except when enough pull is exerted on the eye member 29 to expand the legs of the U-shaped member 30 surliciently for exit oi the cap.

In order to reduce static interference of radio equipments and the like, a coiled spring-like conductor 3! is placed around the fuse tube 2l between the eye member 29 and the bottom of a threaded sleeve 3| ontowhich the cap 22 is threaded whereby to have the eye member at the same potential as the terminal I.

Referring now more particularly to other features of the heretofore described structure, the upper stationary contact means comprises in addition to the leaf contact spring I0 a leaf backing spring It. Both of these springs, as shown more clearly in Fig. 2, are carried by a bracket 32 extendingoutwardly. from the insulator 3 and supported-,therefrom on a Stud 3,;3 mounted in the insulator. For simplicity in mounting, the contact structure I0, Ill' is secured to the bracket 32 by the terminal bolt I which is provided with a shouldered cylindrical nut 34 having a ridged periphery. The smaller diameter portion of the nut 34 ts into a hole in the spring member I0 and clamps the spring contact I0 against the bracket 32, as shown in both Figs. 2 and 5, thereby establishing electrical contact with the spring contact I0. The inner end of the spring I0 is notched and curved upwardly to engage the stud 33 whereby to prevent turning movement. The innerend of the backing spring Iii bears on the curved portion of the contact spring It, and the smaller diameter portion of the nut 3i is somewhat longer than the thickness of the backing spring Iii so as to provide greater freedom of movement of the backing spring. Also, the front end oi' the bracket is bent downwardly so that the Contact spring iB can follow the cap 22 during the iirst part of the dropout action of the switch, as shown in Fig. 4, whereby to maintain continuity of contact until the expulsion action or" the fuse and arc interruption in the tube 2l have occurred. The extreme end of the bracket 32 is further curved downwardly at 35 to provide a support for the U-shaped holding member 39. the base of which is secured to the bracket by suitable means such as a bolt 35 provided with a shock-absorbing head 37 of suitable resilient mau terial to absorb the closing impact. As the switch opens during the dropdown action oi the fuse tube, particularly under small currents which eifect slow melting of the fuse and weak expulsion action, the cap 22 remains in conducting engagement with the holding member 3Q. This provides some delay without circuit interruption at the top whereby to insure arc clearing in the tube 2I.

The fuse tube 2i is supported in a clamp 38 which is pivotally secured to the hinge element i4 at 26. For lateral stability relatively to this element, the lower end of the tube 2I is held between side arms 39 on the element. In order that the toggle comprising the hinge element I4 and the tube 2I may, when held rigid, swing in substantially a true plane and thus align the cap 22 with a relatively narrow entrance of the holding member 3i] so as to be suitable for covering with a hood 52, the hinge element is provided with bearing shoulders il which ride against the inside surfaces of the hooks i3 and from which the trunnions I5 protrude outwardly since this structure is mechanically simple to machine. Also, in order to increase the manufacturing limits for this simple machine operation and for the hooks IB to those of normal low cost manufacture, the bearing member I is provided with dared wing guides 4I with which cooperates a relatively close fitting flange d2 on a supporting leg of the hinge element. The relatively large distances between the trunnions iii and between the guides I makes a more positive guide for directing the cap 22 into the relatively narrow entrance of the holding member 30 than has been achieved in prior art constructions with which I am familiar. To limit the angular movement of the tube ZI relatively to the hinge element I t during the dropout action, the upper end of the supporting leg 43 is provided with an extension 4 which bears against a clamping screw 3S after a predetermined amount of dropout movement has occurred. The hinge element I4 is also provided with an eye member 45 by which the element and the tube `2| can be removed when in the open or i? vertically down position for inspectin, fuse replacement, etc. with the aid of the usual switch hook.

As shown, the lower stationary leaf spring contact I3 is supported on a bracket 45 which is suitably secured to the outside of the rear wall 41 of the bearing member I I. For holding the contact on the bracket d6, the terminal bolt 2 extends through the outstanding leg of the bracket and is provided with a cylindrical clamping nut 48 which has a ridged' periphery and which bears against the contact I3. In accordance with my invention, the contact i3 extends through an opening in the rear wall of the bearing member I I so as to be engaged by the contact I'I on the hinge element Ill when the switch is closed. Also in accordance with my invention, the bearing member II is supported on a stud 49 extending axially downward from the lower end of the insulator 3 substantially in line with the' axis thereof and also substantially in line with the point of engagement of the contacts I3 and I'I. Further in accordance with my invention, I provide shockabsorbing means positioned adjacent the lower end of the insulator and yieldable substantially in the direction of the axis of the insulator for absorbing the eiect of the expulsion force transmitted to the hinge element I4 and thence through stud i9 and insulator 3 to supporting arm fi so the insulator 3 is essentially in compression substantially along the axis thereof upon rupture of the conductor I9 as at the fusible portion 26 thereof. As illustrated, this means comprises a helical compression spring 5U which is positioned around a reduced diameter portion'5I of the stud 19 and between the inside of the upper wall of the bearing member I i and the upper surface of the Contact I3.

Also a resilient bumper 5il, of rubber or the like, is inserted inside the spring 50 and arranged so as to be compressed between the stud 5I and the upper surface of the contact I3 after the spring 5S has been compressed a predetermined amount. Additionally in accordance with my invention, the length o1 the reduced portion of the stud [i9 and the resilient bumper 5U' is such that, even though the hinge element is forcibly lifted by the expulsion shock, the contact I3 will strike and compress the bumper y'rit' a predetermined amount against the end o1" the stud 49 so as to cushion the impact and stop the upward movement before the trunnions I5 are raised far enough to be movable out oi the hooks I6, and also before the upward movement of the tube 2i under the action of the recoil forces has over--l stressed the terminal I and acting through said terminal has imposed a slightly amplified bending stress on the insulator 3.

Again in accordance with my invention, since the bearing axis I2 of the hinge element I4 is to the left of the axis of the insulator 3, the line of action of the force exerted on the hinge element by the compression spring i5 through the contact spring I3 and the contact Il is such that this force tends to maintain a high contact pressure between the contacts I3 and Il. Also, because or" the direction of application of this force, it tends to move the hinge element I4 to the circuit open position whereby to accelerate the opening action when the conductor I9 is ruptured. Also, in order to protect the parts associated with the terminal 2 from the elements, the bearing member II is preferably in the form of a hood Withonly the front and lower sides open. In

against the elements and also tc make this contact structure practically ina-ccessible to wild life, I provide, in accordance with my invention, an improved hood structure which is readily and simply attachable to and detachable from the switch. As shown, this structure comprises a hcod 52 'preferably of insulating material which may be formed by molding or otherwise. For ease in mounting, the bottom of the hood is open and also the front in order to allow passage of the cap 22 to and from the circuit closed position. Also for simplicity in mounting, the rear wall of the hood 52 is notched at 53 to t over the stud 33 between the insulator 3 and the fixed end of the bracket 32, and the top wall 54 is provided with an opening just large enough to slip over and register with the periphery of the cylindrically headed nut 34 on the terminal bolt I. In order to prevent turning of the hood 52 about the head of the nut 34 the interior of the hood is arranged to engage the bracket 32. For clamping the hood in place and also keeping water from entering the hood, I provide a clamping nut 55 and a cupped spring washer :55, as shown more clearly in Figs. l and 5. In order to avoid bending strains on the top wall of the hood 52 under the clamping action, the inside of the top wall is provided adjacent the hole in the wall with transversely extending thick bearing portions 51 which seat on the bracket 32, as shown most clearly in Fig. 5. These portions take in compression the clamping force consequent on tightening the nut 55. Also the hood 52 may be provided with internal stiiening ribs 58, as shown. For securing line conductors to the terminals I and 2, each is provided with a wire clamp 59, a lock washer 5G and a nut 6I, as shown.

From the foregoing, it will be apparent that in consequence of having the supporting arm 4 extend outwardly from the insulator oppositely to the contact structure without the use of a band surrounding the middle ci the insulator, it is possible to bring the contact structure in closer to the insulator without danger of wild life eiTecting short circuits between the contact structure and the supporting arm 4, which is often grounded. Also, because of the compact structure, less room is available for perching birds and the like to alight on the switch and have any material freedom of movement without having to take on". This practically eliminates the possibility of two birds alighting on the switch at the same time and fighting with each other with resultant possibility ci a short circuit across the line. Likewise, the probability of a bird being able to perch on the contact structure and reach around to the supporting arm l is greatly minirnized. Also, with the Contact structure closer into the insulator, the construction is materially stronger and less stress is placed on the insulator due to the decrease in the lever arms. Also, the compactness of structure provides a more pleasing appearance which is further enhanced by the use of the protecting hood 52.

It will be observed that the expulsion type circuit interrupter, comprising the tube 2I and the conductor I9, in the closed position bridges the upper and lower stationary contacts IU and I3 in a direction forming a relatively small acute angle within a range of l to 30 degrees with the longitudinal axis of the insulator 3. The expulsion force on interruption is thus applied to the top and bottom. of the insulator 3 through relatively long and short lever arms, respectively. But since this expulsion force is largely absorbed by the spring Sil and the bumper 50' and the upper travel is limited by the bumper '50 and the stop I, very little of the force is left to produce bending stresses at the top of the insulator 3 and the effect of this little is eased by the resilient action of the spring Contact means I0, IU.

Assuming the switch in the circuit closed position, as shown in Figs. 1 and 2, with the toggle comprising the tube ZI and the hinge element I4 held in the rigid condition against the bias of the contact springs, heli-cal spring 5I) and gravity by the conductor I9, then if sufiicient current ows through the switch to rcelt the fusible portion 2i! of this conductor, the toggle is free to collapse under its bias as soon as the fuse parts. When this occurs, the parts assume the full line condition shown in Fig. 4 with the fuse tube initially being urged downwardly by the resilient action of the contact means I0, I0 and I3 and the helical spring 56. The cap 22 at the upper end of the fuse tube, however, rides downwardly inside of the holding means 30 until the conductor iti blown from the fuse tube .ill whereupon the tube assumes the position Y shown in broken lines in Fig. 4. and also Under the force of gravity and the biasing impulse initially imparted to the tube, the hinge element I4 and the parts associated therewith move in a clockwise direction until the eye 45 of the hinge element contacts the rear wall 4l of the bearing member, as indicated by the broken line position X in Fig. i then nally swing baci: to a vertical position below the insulator under the eifect of gravity.

When it is desired to re-fuse the switch, the hinge element I4 is lifted out of the bearing member I I by using a switch hook or the like in the eye 45. A new fusible element is inserted in the tube 2| after rst removing the cap 22 and then restoring it to lock the fuse head at the top of the tube as is well known to the art. The new fused conductor I9 is then inserted around the clamping bolt 2l and this bolt tightened to lock the fuse so as to hold the toggle rigid. The tube with a new fused conductor I9 in the toggle retaining position is shown in broken lines in Fig. 2 in the position Z just after restoring the hinge element Ifl in the bearing member II. The switch may then be closed by inserting a switch hook in the eye 'is and moving the rigid toggle about the bearing axis I2 into the position shown in full lines in Fig. 2 where the switch is maintained by the holding means 3l! as long as the toggle is held rigid.

The embodiment of my invention shown in Fig. 6 is an adaptation of the fuse dropout switch shown in Figs. l to 5, inclusive, for use as a disconnecting switch nonresponsive to current conditions or for use as a non-dropout type o'f fuse disconnecting switch by fastening the fuse tube 2I to the hingle element it by a screw 63 as shown in Fig. 6. In the case of a disconnecting switch, as shown in Fig. 5, the fuse tube 2i is replaced by a tubular conducting Ymember 52 which is attached to the hinge element I4 in a manner similar to the arrangement shown in the other gures except that, since no relative movement is to take place between the hinge element and the conducting tube 62, the lower end of the tube is also secured to the hinge element to prevent movement about the pivot 25. For this purpose, any suitable means such as a screw 63 projecting through the tube 6I and threaded into the hinge element may be used. To prevent any twisting action of the tube 82, the tube may be notched at 64 so as to seat one of the clamping bolts, not shown, of the clamping means 3 In this modication of my invention, of course, both the circuit opening and circuit closing movements are to be performed manually by means of a switch hook slipped in the eye, not shown, on the 'tubular member E2.

While I have shown and described my invention in considerable deteil, I do not desire to be limited to the exacte-rangements shown, but seek to cover in the appended claims all those modifications that fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

l. An electric switch comprising an insulator, a first contact means supported on said insulator adjacent one end thereof, a hook type bearing member supported from the other end of the insulator, a second Contact means supported ad jacent the other end of the insulator, a hinge element provided with trunnions adapted to be inserted in the hooks of said bearing member, said hinge element having a portion spaced from said other end of said insulator and in line with the longitudinal axis thereof, a Contact on said hinge element cooperating with said second contact means, current conducting means carried by said hinge element and rotatable therewith in one direction to the circuit closed position to establish a conducting path between said two contact means comprising an expulsion tube mounted on said hinge element and having a contact cap engageable with said rst contact means, a conductor mounted in said tube to extend between said cap and said element and provided with a, fusible portion and means for clamping said conductor to said element, and shock-absorbing means including a resilient member positioned between said axially aligned portion of said hinge element and said other end of the insulator and yieldable substantially in the direction of the axis of the insulator for absorbing the effect of the expulsion force transmitted to the hinge element upon rupture of said conductor.

2. An electric switch comprising an insulator, a rst contact means supported on said insulator adjacent one end thereof, a hook type bearing member supported from the other end of the insulator, a second contact means supported adjacent theother end of the insulator, a hinge element provided with trunnions adapted to be inserted in the hooks of said bearing member, said hinge element having a portion spaced from said other end of said insulator and in line with the longitudinal axis thereof, a contact on said hinge element cooperating with said second contact means, current conducting means carried by said hinge element and rotatable therewith in one direction to the circuit closed position to Lestablish a conducting path between said two contact means comprising an expulsion tube mounted on said lhinge element and having a contact cap engageable with said first contact means,

i a conductor mounted in said tube to extend between said cap and said element and provided with a fusible portion and means for clamping said conductor to said element, and means for absorbing the effect of the expulsion force transmitted ,to the hinge element and limiting the upward movement thereof upon rupture of said conductor comprising a stud centrally mounted in said insulator at said other end thereof in line with the path of upward movement of the contact on said hinge element and a helical compression spring around said stud between the insulator and said axially aligned portion of said hinge element.

-' 3. `An electric switch comprising an insulator, a first contact means supported on said insulator adjacent one end thereof, a hook type bearing member supported from the other end of the insulator, a second contact means supported adjacent the other end of the insulator, a hinge element provided with trunnions adapted to be inserted in the hooks of said bearing member, said hinge element having a portion spaced from said other end of said insulator and in line with the longitudinal axis thereof, a conta-ct on said hinge element cooperating with said second contact means, current conducting means carried by said hinge element and rotatable therewith in one direction to the circuit closed position to establish a conducting path between said two contact means comprising an expulsion tube pivotally mounted on said hinge element and having a contact cap engageable with said first contact means, a conductor mounted in said tube to extend between said cap and said element and provided with a fusible portion and means for clamping said conductor to said element t hold the element and the tube against relative movement until rupture of the conductor, and means for absorbing effect of the expulsion force transmitted to the hinge element upon rupture of said conductor comprising a helical compression spring mounted between said axially aligned portion of said hinge element and said other end of the insulator with its axis substantially in line with the axis of the insulator.

V4. In a fuse disconnecting switch of the open dropout type, an insulator, a first contact means supported on said insulator adjacent one end thereof, a hook type bearing member supported from the other end of the insulator in line with the longitudinal axis thereof, a second contact means supported on said bearing member, toggle means for establishing a conducting connection between said two contact means comprising a hinge element having trunnions insertable in the hooks of said bearing member and carrying a contact engageable with said second contact means and an expulsion fuse tube pivotally associated with said element and carrying at its free end a contact cap adapted to cooperate with said first contact means, said contact carried by said hinge element being spaced from said other end of said insulator and in line with the longitudinal axis thereof, means for holding said toggle rigid comprising a conductor in said tube extending from said cap t0 said element and secured thereto, said conductor having a fusible portion, means for maintaining said toggle While rigid with said contact cap in engagement with said rst contact means and the contact on said element in engagement with said second contact means, and a resilient member interposed between said contact carried by said hinge element and said other end of the insulator and yieldable substantially in the direction oi' the axis thereof for absorbing the expulsion force transmitted to the hinge element upon rupture of said conductor.

5. An electric switch comprising an insulator, a first relatively stationary contact means supported on said insulator adjacent one end thereof to extend transversely from the insulator, a hook type bearing member supported from the other end of the insulator in line with the longitudinal axis thereof with its bearing axis substantially perpendicular to the longitudinal axis of the insulator and displaced from said axis oppositely to the displacement of the first stationary contact means, a second relatively stationary contact means mounted cn said bearing member, a hinge element provided with trunnions adapted to be inserted in the hooks of said bearing member, a contact on said hinge element movable therewith into and out of 'engagement with said second relatively stationary contact means upon rotation of said hinge element, said contact on said hinge element being spaced from said other end of said insulator and in line with the longitudinal axis thereof, current conducting means carried by said hinge element and rotatable therewith in one direction to the circuit closed position to establish a conducting path between said two stationary contact means compris-1 ing an expulsion tube pivotally mounted on said hinge element and having a contact cap engageable with said iirst stationary contact means, a conductor mounted in said tube tc extend between said cap and said element and provided with a fusible portion and means for clamping said conductor to said element to hold the element and the tube against relative movement until rupture of the conductor, resilient means positioned between said other end cf the insulator and said second contact and hinge element contact engageable therewith to exert on said second contact means a force substantially in line with the axis of the insulator whereby to maintain a relatively high contact pressure between the second stationary contact means and the contact on the hinge element and whereby to tend to rotate the element in the circuit opening direction of said conducting means and to absorb the effect of the expulsion force transmitted to the hinge element upon rupture of said conductor. and means adjacent said rst staticnary contact means for maintaining said current conducting means and said hinge element in the circuit closed position.

6. An electric switch comprising an insulator, a first relatively stationary contact means supported on said insulator adjacent one end thereof to extend transversely from the insulator, a hook type bearing member supported from the other end of the insulator in line with the longitudinal axis thereof with its bea-ring axis substantially perpendicular to the longitudinal axis of the insulator and displaced from said axis oppositely to the displacement of the first stationary contact means, a second relatively stationary contact means mounted on said bearing member, a hinge element provided with trunnions adapted to be inserted in the hooks of said bearing member, a contact on said hinge element movable therewith into and out of engagement with said second relatively stationary contact means upon rotation of said hinge element, said contact on said hinge element being spaced from said other end of said insulator and in line'with the longitudinal thereof, current conducting means carried by'said hinge element and rotatable therewith in one direction to the circuit closed position to establish a conducting path between `said two stationary Contact means, resilient means positioned between said other end of the insulator and said second contact and hinge element ccntact engageable therewith to exert on said second contact means a force substantially in line with the axis of the insulator whereby to maintain a relatively high contact pressure between the second stationary contact means vand the contact on the hinge element and whereby to tend to rotate the element in the circuit opening direction of said conducting means, and means adjacent said rst stationary Contact means for maintaining said -current conducting means and said hinge element in the circuit closed position.

7. An electric switch comprising an insulator, a first relatively stationary contact means supported on said insulator adjacent one end thereof -to extend transversely from the insulator, a hook type bearing member supported from the other end of the insulator in line with the longitudinal axis thereof with its bearing axis substantially perpendicular to the longitudinal axis of the insulator and displaced from said axis oppositely to the displacement of the rst stationary contact means, a second relatively stationary contact means mounted on said bearing member, a hinge element provided with trunnions adapted to be inserted in the hooks of said bearing member, a contact on said hinge element movable therewith into and out of engagement with said second relatively stationary contact means upon rotation of said hinge element, 'said contact on said hinge element being spaced from said other end of said insulator and in line with the longitudinal axis thereof, current conducting means carried by said hinge element and rotatable therewith in one direction to the circuit closed position to establish a conducting path between said two stationary contact means comprising an expulsion tube pivotally mounted on said hinge element and having a contact cap engageable with said rst stationary contact means,

a conductor mounted in said tube to extend between said cap and said element and provided with a fusible portion and means for clamping said conductor to said element to hold the element and the tube against relative movement until rupture of the conductor, and a helical compression spring positioned between said other end of the insulator and said second contact and hinge element contact engageable therewith to exert on said second contact means a force substantially in line with the axis of the insulator whereby to absorb the effect of the expulsion force transmitted to the hinge element upon rupture of said conductor.

8. In a fuse disconnecting switch of the open type, a supporting insulator, a bracket projecting from said insulator adjacent one end thereof and extending transversely of the insulator, stationary contact means supported on said bracket, movable contact means engageable with said stationary contact means, a terminal bolt and nut for securing said contact means to said bracket, means for sheltering the top and sides of said contact means comprising a hood having its top wall provided with an opening registrable with the periphery of the nut on said terminal bolt, fastening means engageable with said terminal bolt to maintain said hood firmly in position on said bracket and separate latching means independent of said hood secured to said bracket for maini contact 14 taining said stationary and movable contact means in engagement.

9. In a fuse disconnecting switch of the open type, a supporting insulator, a stud projecting from said insulator adjacent one end thereof and extending transversely of the insulator, a contact terminal bracket secured to said stud and extending transversely of the insulator, leaf spring Contact means iixedly mounted on said bracket and provided with a notched portion in engagement with said stud, a terminal bolt and nut for securing saidcontact means to said bracket, movable contact means engageable with said fixedly mounted contact means, a hood of insulating material having its top wall provided with an opening just large enough to register with the periphery of the nut on said terminal bolt, and fastening means engageable with said terminal bolt to hold said hood irrnly in position on said bracket and separate lai-:hing mea-ns independent of said hood for maintaining said xedly mounted and movable contact means in engagement.

10.3111 a fuse disconnecting switch of the open type, an insulator, a stud projecting from said insulator' adjacent one end thereof and extending transversely of the insulator, a contact terminal bracket secured to said stud and extending transversely of the insulator, leaf spring contact means, a terminal bolt and nut for securing said contact means to said bracket, contact means mounted 011 said insulator near the other end thereof, fused conducting means pivotally associated with the insulator adjacent said other end thereof and movable into engagement with said leaf spring means to complete a conducting path therefrom to the contact means mounted on the other-end of the insulator, a hood of insulating material having a notched rear wall adapted to be'slipped over said stud between the insulator and the xed end of the bracket and having its top wall provided with an opening just large enough to register with the periphery of the nut on vsaid terminal bolt, fastening means engageable with said terminal bolt to hold said hood in place on said bracket, said hood having front and bottom openings to permit the angular movement of said conducting means into engagement with said leaf spring contact means and the dropout of said fused conducting means upon rupture thereof and separate lat-ching means independent of said hood secured to said bracket for maintaining said conducting means in the circuit closed position.

11. An electric circuit interrupter comprising an insulator, a rst contact means mounted on said insulator adjacent one end thereof and extending transversely of the insulator, a second contact means mounted on the other end of said insulator, holding means having relatively narrow flaring arms associated in compact arrangement with said first contact means, a hook type bearing member supported from the other end of said insulator and associated with said second contact means, said bearing member having flaring arms, a hinge element provided with trunnions adapted to be inserted in the hooks of said bearing member, said hinge element having a flange portion extending transversely with respect to said ilaring' arms and movable in guiding relation between and engageable with said arms of said bearing member, and circuit interrupting means mounted on said hinge element for pivotal movement into and out of bridging position with said contact means.

12. An electric circuit interrupting device comprising aninsulating support, a first contact means mounted on said support adjacent one end thereof, a second contact means mounted on the other end of said support, hinge means associated With said second contact means, said hinge means having a portion spaced from said otherI end of said insulating support and in line with the longitudinal axis thereof, a circuit interrupter mounted on said hinge means for pivotal movement into and out of a bridging position for electrically interconnecting said contact means, said interrupter exerting a force on said hinge means during circuit interruption, and a member interposed between said axially aligned portion of said hinge means and said other end of said support for absorbing said force and transmitting it to said insulating support substantially in compression thereon along the axis of the support.

13. An electric circuit interrupting device comprising anY insulating support, a first Contact means mounted on said support adjacent one end thereof and extending transversely vof the support, a second contact means mounted on the other end of said insulating support, hinge means associated with said second contact means, said hinge means having a portion spaced from said other end of said support and in line with the longitudinal axis thereof, a circuit interrupter mounted on said hinge means for pivotal movement into and out of a bridging position for electrically interconnecting said contact means, said interrupter exerting a force on said hinge means during circuit interruption in a direction away from the hinge means and toward said rst contact means, a shock-absorbing member interposed between said axially aligned portion of said hinge means and said other end of said support for absorbing said force and transmitting it to said insulating support substantially in line with the axis thereof, and means associated with said shock-absorbing member for limiting the movement of said circuit interrupter whereby to minimize the bending stress on said insulating support as imposed through said rst contact means.

14. An electric circuit interrupting device comprising a cylindrical insulator, a first contact means mounted on said insulator adjacent one end thereof and extending outwardly from the insulator, a second contact means mounted on the other end of said insulator, an expulsion type circuit interrupter for electrically interconnecting said contact means in a direction forming an acute angle Within a range of 10 to 30 degrees with the longitudinal axis of said insulator and spaced therefrom whereby the force exerted during circuit interruption is transmitted to said insulator through relatively short and long lever arms, said short lever arm comprising a support with said circuit interrupter mounted thereon and having a portion spaced from said other end of said insulator and in line with the longitudinal axis thereof, means mounted between said axially aligned portion of said support and said other end of said insulator for absorbing said force and transmitting it to said insulator substantially in line with the longitudinal axis thereof, and means associated with said force absorbing means for limiting the portion of said force exerted on said first contact means.

WILLIAM C. LESHER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,075,170 Brown Mar. 30, 1937 2,176,227 Schultz et al Oct. 17, 1939 2,265,521 Elliott Dec. 9, 1941 2,267,202 Holmes et al Dec. 23, 1941 2,323,213 Garrison June 29, 1943 2,324,888 Strobel July 20, 1943 2,328,818 Lindell et al Sept. 7, 1943 2,333,217 Triplett Nov. 2, 1943 2,357,772 Schultz Sept. 5, 1944 2,493,432 Yonkers Jan. 3, 1950 2,493,433 Yonkers Jan. 3, 1950 FOREIGN PATENTS Number Country Date 25,885 Great Britain Dec. 18', 1901 

